1990 U.S. Proof Set 5-Coin. Just 2.8 million ever existed (far below the maximum 4.1 million mintage of 1976) and many were broken up to obtain individual Kennedy half dollar proofs.
1990 U.S. Mint Set 10-Coin. The 1990 U.S. Mint Set had a final mintage of 1.8 million, far below the 1987 mint set's production of 2.9 million.